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(4x - 3)(3x + 1)
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\(3x\left(4x-3\right)-\left(2x-1\right)\left(6x+5\right)\\ =12x^2-9x-\left(12x^2+10x-6x-5\right)\)
\(=12x^2-9x-\left(12x^2+4x-5\right)\\ =5-13x\)
Lời giải:
a.
$5x-[2x+1-(2x-3)-(4x+1)]=5x-(2x+1-2x+3-4x-1)$
$=5x-(-4x+3)=5x+4x-3=9x-3$
b.
$(-3x^2+2x-1)+(4x^2-2x+3)$
$=-3x^2+2x-1+4x^2-2x+3=x^2+2$
a: \(=15x^4-12x^3+9x^2\)
c: \(=5x^3-15x^2-4x^2+12x\)
\(=5x^3-19x^2+12x\)
`@` `\text {Ans}`
`\downarrow`
`a)`
\(2x(4x²+x-3)\)
`= 2x*4x^2 + 2x*x + 2x*(-3)`
`= 8x^3 + 2x^2 - 6x`
`b)`
\([(-9x)+4x]: (-3x)-3x²\)
`= (-9x) \div (-3x) + 4x \div (-3x) - 3x^2`
`= 3 - 4/3 - 3x^2`
`= 5/3 - 3x^2`
Ta có: \(\left(\dfrac{x+2}{3x}+\dfrac{2}{x+1}-3\right):\dfrac{2-4x}{x+1}\cdot\dfrac{3x}{x^2-3x-1}\)
\(=\left(\dfrac{\left(x+2\right)\left(x+1\right)}{3x\left(x+1\right)}+\dfrac{6x}{3x\left(x+1\right)}-\dfrac{9x\left(x+1\right)}{3x\left(x+1\right)}\right):\dfrac{2-4x}{x+1}\cdot\dfrac{3x}{x^2-3x-1}\)
\(=\dfrac{x^2+3x+2+6x-9x^2-9x}{3x\left(x+1\right)}\cdot\dfrac{x+1}{2-4x}\cdot\dfrac{3x}{x^2-3x-1}\)
\(=\dfrac{-8x^2+2}{3x\left(x+1\right)}\cdot\dfrac{x+1}{2-4x}\cdot\dfrac{3x}{x^2-3x-1}\)
\(=\dfrac{-2\left(4x^2-1\right)}{3x\cdot2\cdot\left(1-2x\right)}\cdot\dfrac{3x}{x^2-3x-1}\)
\(=\dfrac{2\left(1-2x\right)\left(2x+3\right)}{6x\left(1-2x\right)}\cdot\dfrac{3x}{x^2-3x-1}\)
\(=\dfrac{2x+3}{x^2-3x-1}\)
a: \(=2x^3:\dfrac{-3}{2}x+4x:\dfrac{3}{2}x-5:\dfrac{3}{2}\)
=-4/3x^2+8/3-10/3
=-4/3x^2-2/3
d: \(\dfrac{3x^3-5x+2}{x-3}=\dfrac{3x^3-9x^2+9x^2-27x+22x-66+68}{x-3}\)
\(=3x^2+9x+22+\dfrac{68}{x-3}\)
a) ( 3x + 2y - 1 )( x - 5 ) - ( x - 2 )2y
= 3x(x - 5) + 2y(x - 5) - 1(x - 5) - ( 2xy - 4y )
= 3x2 - 15x + 2xy - 10y - x + 5 - 2xy + 4y
= 3x2 - 16x - 6y + 5
b) ( 3x - 2 )( 3x + 2 ) - ( 2x + 1 )( 4x + 3 )
= [ ( 3x )2 - 22 ] - ( 8x2 + 10x + 3 )
= 9x2 - 4 - 8x2 - 10x - 3
= x2 - 10 - 7
\(\left(3x^{n+1}-2x^n\right).4x^2=12x^{n+3}-8x^{n+2}\)
\(\frac{4x+1}{3x}+\frac{2x-3}{6x}\)
\(=\frac{2\left(4x+1\right)}{6x}+\frac{2x-3}{6x}\)
\(=\frac{2\left(4x+1\right)+\left(2x-3\right)}{6x}\)
\(=\frac{8x+2+2x-3}{6x}\)
\(=\frac{10x-1}{6x}\)
(4x - 3)(3x + 1)
= 12x2 + 4x - 9x - 3
= 12x2 - 5x - 3